In monitoring the firmness of tobacco rods in cigarette manufacture, the industry has made extended use of compacimeters (compactness meters) whereby exacting "off-line" measurements can be made on manufactured cigarettes without intervention in the making process. In its further efforts to provide tobacco rod firmness information more contemporaneous with cigarette manufacture, thereby to enable adjustment or correction of the parameters of the making process concurrently with information gathering, the industry has looked further to various "on-line" systems and apparatus. Versions of pneumatic apparatus are shown in U.S. Pat. Nos. 3,411,513, 3,595,067, 3,633,590 and 3,850,029 and in British Pat. No. 1,372,056. These devices are (1) of type employing floating nozzles issuing pressurized air onto the cigarette wrapper and either measure deformation of the wrapper or displacement of the nozzle based on change in back pressure and (2) of type providing a pressurized on-line chamber arrangement and observing pressure changes caused by variation of firmness or dimensions of cigarettes passing therethrough.
Alternate, non-pneumatic approaches to firmness measurement are set forth in U.S. Pat. No. 2,667,172 and South African Patent Application No. 73/9394. The devices of the 2,667,172 patent and such patent application look toward the use of tobacco rod forming elements of existing maker machinery for the additional function of providing output indication of rod firmness. In the 2,667,172 patent, elongate short tongue 60 includes strain gages 116 and 116a positioned proximate its compression foot and distal from short tongue support clamp or beam 101. These gages are in spaced longitudinal alignment whereby longitudinal pressures exerted by tobacco against the tongue may be sensed. This sensing apparatus is separate in function and operation from the tobacco rod firmness sensing apparatus of the 2,667,172 patent. The latter apparatus comprises a single active strain gage 84, also disposed between the tongue support beam and foot and adapted to provide output indication of vertical strain placed on the short tongue, i.e., movements of its foot transverse to the direction of movement of tobacco engaged thereby. The South African patent application relates also to specially constructed short tongues, disclosing a first embodiment wherein the compression foot of a short tongue is split into two successive longitudinal sections, each having a separate support flange with one support flange having a strain gage thereon, and a further embodiment wherein the longitudinally forward of such compression foot sections is further split into three circumferential segments, each having an independent support flange with a strain gage thereon. Such support flanges are stems having one end terminating at the compression foot and an opposite end terminating at the tongue cantilever support beam.